Ceramic materials have enjoyed great success as igniters in gas-fired furnaces, stoves and clothes dryers. A ceramic igniter typically includes a ceramic hot surface element having a conductive end portion and a highly resistive portion. When the element ends are connected to electrified leads, the highly resistive portion (or “hot zone”) rises in temperature. See, generally, U.S. Pat. Nos. 3,875,477, 3,928,910, 3,974,106, 4,260,872, 4,634,837, 4,804,823, 4,912,305, 5,085,237, 5,191,508, 5,233,166, 5,378,956, 5,405,237, 5,543,180, 5,785,911, 5,786,565, 5,801,361, 5,820,789, 5,892,201 and 6,028,292.
Since these igniters are resistively heated, each of its ends must be electrically connected to a conductive lead, typically a copper wire lead. However, problems are associated with connecting the ceramic hot surface element ends to leads. One issue has been bonding of the ceramic material and the lead wire do not bond well together. See EP 0486009, which uses a combination of braze and solder for affixing the ceramic and the lead wire. For a number of reasons, use of solder is less desirable, however, including a relatively laborious process as well as frequent damage of the ceramic igniter element by the high temperature (e.g. 1600–1800° C.) solder application.
Efforts have been made to manage problems caused by solder connections. For example, U.S. Pat. No. 5,564,618 to Axelson recognized that the CTE mismatch between the braze and the solder was causing breakage during the soldering step, and sought to minimize the braze by using a silk screening approach. U.S. Pat. No. 6,440,578 reports certain solder materials said to provide improve bonding properties. See also U.S. Pat. No. 6,635,358.
Other efforts have sought to eliminate solder from ceramic igniter termination systems, but these approaches have generally in either fragile or temporary systems. See, for instance, GB 2,059,959, which describes a redundancy of mechanical support for the hot surface element-electrical lead indicates that the reported solderless connection is relatively insecure. U.S. Pat. No. 5,804,092 reports a certain modular ceramic igniter system, in which the ceramic hot surface element is plugged into a socket having a conductive contact therein.
A highly useful ceramic igniter that does not employ solder for electrical connections is disclosed in U.S. Pat. No. 6,078,028 of Saint-Gobain Industrial Ceramics, Inc. Additional highly useful methods for producing ceramic igniters are disclosed in U.S. Pat. Nos. 5,564,618 and 5,705,261 and U.S. Published application 2003/0080103.
In addition to the difficulties to securely attach electrical connections to ceramic igniter elements, the affixation process can be laborious. See, for instance, U.S. Pat. Nos. 6,440,578 and 6,635,358.
It thus would be desirable to have new ceramic igniters that could provide enhanced performance properties. It would be particularly desirable to have new methods and systems that could provide a secure electrical connection to a ceramic igniter. It also would be particularly desirable to have new improved methods and systems for producing ceramic igniters.